Doee any one know why would this be done?

A friend had his engine rebuild by a well known rotary engine builder, and he did a streetport and the guy also made the trailling hole bigger. and i was wondering what are the benefits of doing this.

 

Come on somebody has to have a idea why this is done. or maybe a theory why?

 

Trailing plug holes have to be small to minimize gas leakage from chamber with combustion to chamber which just finishes intake cycle. It hurts both ways, loss of combustion pressure is obvious, but also, hot gases displace portion of fresh intake charge. Same goes for far trailing system on R26B - paper exactly states, that there was noticeable BSFC improvement due to better combustion with 3rd plug, but power improvement wasn´t of such magnitude due to gas leakage minimizing VE.

So to answer your question, I don´t see how making trailing hole bigger would be benefical to anything. If the builder is reputable, he certainly should explain why he did such "modification". Otherwise it would seem that he is experimenting on customers engine

 

or drilling out some cracks

 

Thank you for your input. I Also think he was trying something strange.

 

He does have a few car running low 7sec. With his engines. But i still don't know why he would do this. And for a street car running stock turbo.

 

Beat me to it. I've seen it to remove hairline cracks; cracks that usually you can barely see. There's several ways to avoid cracks from the get go...